19th November 2017, 5:48 Edited(This post was last modified: 19th November 2017, 6:03 by AJSlye.)

The xorg-twm package has always been installed on Manjaro by default as a backup.
The lines you listed are supposed to be there so that twm is started by default when you use xinit/startx from the console.
Otherwise, what would be the point of including twm as a backup when Plasma5/kwin or your DM doesn't want to load and you need to fix something.

Starting the the correct desktop is the job of the DM, If SDDM didn't start Plasma 5 as it was supposed to, then there is something else wrong on your system.

19th November 2017, 6:11 Edited(This post was last modified: 19th November 2017, 6:14 by AJSlye.)

SDDM is used to start the plasma desktop, it's not using /etc/X11/xinit/xinitrc.
All the machines here running NRR logged into the Plasma desktop just fine via SDDM after every update.
I'm not sure why your having this as an issue, unless you have a ~/.xinitrc file in your home directory for some reason.

19th November 2017, 7:36 Edited(This post was last modified: 19th November 2017, 13:11 by AJSlye.)

Once again, xinitrc is irrelevant if you are using a display manager (SDDM).
Startx does use xinitrc however, in-which twm would be the desired outcome on a Manjaro based system.
Twm is there so that the user still has a wm to use in case Plasma/kwin is broken.
I think you may have done something to your system that changed the way in which autologin is supposed to work.

I'm glad to hear you got your bluetooth speakers working.
However, all the required packages for bluedevil and bluez are installed by default.
If a users hardware requires the bluez-firmware package, then they'll need to install that themselves.
Installing bluez-firmware by default causes issues with other Broadcom chips.